The present invention relates to an apparatus for disinfecting and sterilizing dental handpieces. These instruments are characteristic in having narrow, through-going channels for cooling water and for either a rotary driving shaft for a drilling head or for an air flow for driving a turbine. A need has arisen for effecting a complete disinfection/sterilization of these instruments between uses for successive patients, and different systems for this purpose have already been developed, see for example EP-B-0,300,945 and U.S. Pat. No. 5,552,113.
In connection with the invention special attention if paid to the system type, in which the instruments are subjected to autoclaving, preferably after a flush cleaning of the channels. By the autoclaving and the associated generation of steam the exterior surfaces of the instruments will be effectively sterilized, but an effective sterilization of the channels will not be automatically effected thereby.
According to U.S. Pat. No. 5,552,113 it is proposed to feed the steam into the autoclaving chamber by forcing the steam through the said channels from an exterior steam generator, but even though the channels may thereby be effectively sterilized, the general autoclaving of the instruments will be inferior to what is achievable in an ordinary autoclave, where the steam is generated inside the treating chamber, in which the sterilizing effect, widely due to condensation on the instruments, is more pronounced. Such a xe2x80x9cprimaryxe2x80x9d autoclaving with internal steam generation is know from WO 96/00534, where the inlets to the channels in relevant instrument holders or adaptors are used for letting in flushing water, whereby this flushing water is collected in the treating chamber and subsequently heating inside that chamber for primary steam generation therein.
With the present invention is has been recognized that the inlet to the narrow channels, normally comprising a holding stub sealingly communicating with the channels at the handle root end of the instrument and, itself, being connected with relevant supply sources through pipe or hose means, may alternatively be used as an outlet, namely by a forcing out of autoclave steam from the treating chamber through the narrow channels. This may be arranged without any kind of connector means between the treating chamber and the free tips of the instruments since these, as far as the steam is concerned, will be inherently exposed to the steam pressure inside the chamber. Of course, any inlet connection in the holding stub, if also used for outletting purposes, should be connectable to the relevant channels means through a valve system for connecting the channel means selectively to an inlet medium source or to a drain outlet.
Another feature of the present invention is that use is made of an external steam generator, preferably mechanically built directly together with the treating chamber and delivering the steam directly into the treating chamber, thus avoiding special pipe or hose connections between the steam generator and each of the instrument holding stubs.
Additionally, the delivery of the steam from the external steam generator, in which the steam temperature and pressure can be brought up to a relatively very high level, will condition a high degree of temperature control with respect to the temperature of the steam as passing through the said channels, inasfar as any relevant temperature sensor can be placed in the treating chamber itself and not in connection with the channels or associated steam supply pipe means.